#define _CRT_SECURE_NO_WARNINGS 1

* Definition for a binary tree node.
* struct TreeNode {
    *int val;
    *TreeNode* left;
    *TreeNode* right;
    *TreeNode() : val(0), left(nullptr), right(nullptr) {}
    *TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
    *TreeNode(int x, TreeNode* left, TreeNode* right) : val(x), left(left), right(right) {}
    *
};
*/
class Solution {
public:
    string tree2str(TreeNode* root)
    {
        if (root == nullptr)
        {
            return "";
        }
        string ret = to_string(root->val);

        if (root->left || root->right)
        {
            ret += '(';
        }
        ret += tree2str(root->left);

        if (root->left || root->right)
        {
            ret += ')';
        }


        if (root->right)
        {
            ret += '(';
        }
        ret += tree2str(root->right);


        if (root->right)
        {
            ret += ')';
        }



        return ret;

    }
};